The timing of pubertal maturation has been associated with substance use in both boys and girls, but the exact mechanisms by which maturation influences substance use are unclear. Early maturing girls are more likely to use substances at an early age compared to non-early maturers, while both early and late maturing boys appear to be at increased risk for substance use compared to on-time maturers. The proposed project utilizes an existing data set of over 1000 mostly at-risk children to examine moderators and mediators of the relation between pubertal maturation and initiation and use of tobacco, alcohol, marijuana, and inhalants. This investigation focuses on 3 domains-family, peer, and individual differences-and incorporates probable gender differences in each of these domains. The proposed study: (1) examines the relation between pubertal timing and tobacco, alcohol, marijuana, and inhalant use in young adolescents; (2) examines gender differences in the pathways linking pubertal timing with substance use, (3) examines moderating effects of family factors on the relation between pubertal timing and substance use, and (4) examines mediating effects of peer factors and emotional distress on the relation between pubertal timing and substance use. Knowledge of risk and protective factors associated with off-time maturation can aid in identifying populations at increased risk of early substance use and can help target and refine prevention programs. [unreadable] [unreadable] [unreadable]